Burosumab (KRN23) from Ultragenyx Pharmaceutical Inc. and Kyowa Hakko Kirin Co. Ltd. met the primary endpoint of an increase in serum phosphorous levels in a Phase III clinical trial testing the biologic in adults with X-linked hypophosphatemia (XLH), but the limited effect on certain secondary endpoints could reduce the product candidate's use in the rare bone-destroying disease.
Ultragenyx believes that burosumab's effects on three measures that impact XLH patients' quality of life will improve beyond the 24-week...